Milk folate but not milk iron concentrations may be inadequate for some infants in a rural farming community in San Mateo, Capulhuac, Mexico

Background: We were interested in identifying possible nutritional reasons for growth faltering among breastfed infants in the rural farming community of San Mateo, Capulhuac, Mexico (2800 m above sea level). Objective: We examined the prevalence of inadequate iron and folate status among lactating Otomi women and determined to what extent their iron and folate nutriture influenced the milk concentrations of these nutrients. Design: Lactating women (n = 71) provided blood and milk samples and dietary information at a mean ([+ or -] SD) of 22 [+ or -] 13 d postpartum. Blood indexes included hemoglobin, hematocrit, serum iron, total-iron-binding capacity, ferritin, transferrin receptor, mean cell volume, plasma folate, and erythrocyte folate. Results: Approximately 62% and 58% of the women had nutritional anemia defined as a hemoglobin concentration [less than or equal to] 133 g/L and a hematocrit value of 41.0%, respectively. With the use of a 3-index iron assessment model, 2 of the 66 women whose iron status was assessed (3%) had iron-deficient erythropoiesis, and 24 (36%) had iron deficiency anemia. Among the 67 women whose folate status was assessed, 29 (43%) had a low plasma folate concentration, and 13 (19%) had a low blood folate concentration in conjunction with a low hemoglobin concentration. Milk iron content was unrelated to maternal iron status, and the milk provided more than adequate amounts of iron to the infants. In contrast, the infants' predicted folate intake was [approximately equal to] 45 [micro]g/d, or 70% of the current recommended intake. Conclusion: Milk folate concentrations in Otomi women are low and may not support optimal folate status in all breastfed infants. KEY WORDS Iron status, folate status, lactation, milk folate, milk iron, iron-folate interaction